Eating disorders have gone viral. Online communities that promote self-harm flock under social media tags like #thinspiration (thin + inspiration), #proana (pro-anorexia) and #promia (pro-bulimia). Google (actually, don’t) “pro-ana” or other “thinspo” buzzwords and you’ll see literally thousands of message boards, websites, social media accounts and other dark little Internet hideaways home to what are …